JPH0287082A - In-circuit tester with probe pin contact failure determination function - Google Patents

Abstract

PURPOSE:To enable/accurate inspection of appropriateness of a state of contact of each probe pin in a short time by providing CPU for inspecting the quality of each component itself and also the appropriateness of the state of contact of the probe pin. CONSTITUTION:Probe pins 34 are provided in large numbers on a fixture fixing a package board to be inspected, and they are brought into contact respectively with a corresponding measuring land of a discrete pattern provided on the board. A multiplexer 36 is interposed on a channel connecting the pins 34 with a measuring element of a main body, and by arbitrary selection and changeover in measurement, it turns ON or OFF the measuring element and each of the pins 34. An arithmetic device 40, which is composed of CPU 46, specifies pins 34 employed for measurement of a component judged to be faulty and conducts measurement of an electrical characteristic of other components for which said pins are employed commonly for measurement. Then, it executes the inspection of the quality of these components and counts the number of faulty components. When this count number is a prescribed value, e.g. 2, it judges the specified probe pin to be faulty in contact. According to this constitution, judgement is made automatically as to which is faulty, the components themselves or the contact of the probe pin, and thus a time required for judging the quality and the appropriateness is shortened.

Description

Detailed Description of the Invention Field of the Invention The present invention relates to an in-circuit tester used to determine the quality of a mounted board, and particularly relates to an in-circuit tester that uses a fixture equipped with probe pins as a measuring jig for a mounted board. .

2. Description of the Related Art Conventionally, an in-circuit tester has been used to determine the quality of a mounted board, that is, a printed circuit board to which a large number of electrical components are soldered, in order to measure the electrical characteristics of those components. There are two types of in-circuit testers: press type and vacuum type, depending on the method of fixing the mounting board to the tester during measurement. In the press type, as shown in FIG. 5, a mounting board 12 having electrical components 10, etc. is placed on a fixture 16, which is an inspection jig, and has a plurality of probe pins 14 upright, and a plurality of presser rods 18 are pushed downward. Press plate (
(not shown) is lowered from above, clamped, and fixed. At that time, originally the tip of each probe pin 14 should be connected to the electrical component 10.
It is necessary to make contact with all the lids 20 etc. that protrude from the main body.

However, the wiring pattern of the mounting board 12 is composed of a plurality of, for example, three independent patterns 22, 24, and 26, as shown in FIG. Therefore, in reality, one location for each independent pattern, for example, a measurement land 28 consisting of a lead hole at one end or in the middle and a pattern around it, is determined as the inspection point, and contact is made with the independent pattern only at that point with appropriate pressure. It is sufficient to erect one probe pin 14 to do so. Usually, the wiring pattern on the board is composed of a large number of independent patterns, and therefore, a correspondingly large number of probe pins are required. In the figure, 30 is a positioning guide pin that protrudes vertically from the mounting base plate (not shown) and is inserted into holes provided at each of the four corners of the mounting board 12 and the fixture 16, and 32 is each probe pin. 14 and the measuring section of the main body are electrically connected with a lead wire that transmits the measured information.In addition, in the vacuum type, the mounting board is sucked onto a fixture with probe pins set up and fixed.

Therefore, in order to actually measure the electrical characteristics of each component such as resistors, capacitors, and coils, it is necessary to
By passing a measurement current or applying a measurement voltage to each component through each channel connected to those probe pins, the resistance (R〉, capacitance fi (C),
Values such as inductance (L) will be obtained. In addition,
The object to be measured is not limited to general electrical parts, but can be anything that generates voltage, so short circuits between independent patterns, open states, etc. are the same as in general testers.

Problems to be Solved by the Invention However, such in-circuit testers do not have a function of determining poor contact between a mounting board to be tested and a fixture, that is, whether the contact state of the tip of the probe pin with the measurement land is good or bad.

Therefore, users have been combining existing functions of in-circuit testers to determine contact failures of probe pins.

For example, the judgment results can be displayed in a table showing the measurement status and judgment results regarding the electrical characteristics of each part displayed on the screen.
NG such as 0VER which is outside the OD range (No GOO
D> (horizontal column showing measurement status and judgment results for each component), the H-PIN (probe pin that contacts the signal source side of the component) or L-PIN of that step
Find other steps that use the same probe pin number as (the probe pin that contacts the measurement side of the part), and as shown in Table 1 below, for step ■, there are also zeros for steps ■ and ■.
When there was a determination of VER, it was assumed that the H-PIN1 had a poor contact, and as shown in Table 2, when there was a determination of GOOD in steps ■ and ■ for step ■, it was assumed that the component R3 itself was defective.

In each table, NAMERI to R4 indicate each component, and mode R indicates resistance measurement.

In addition, in order to make more accurate judgments, a pin search is performed on the probe pins of the steps that indicate NG, and the parts are tested by measuring their electrical characteristics with a general tester. Note that pin search is an inspection to check the contact condition of the probe pin attached to the fixture V- and the presence or absence of breakage of the lead wire connected to it. If there is a defect in any of the probe pins, no display will appear on the screen, indicating that there is a contact failure in the probe pin or a break in the lead wire.

However, these judgments cannot be made without specialized knowledge, and since they are made by humans, there is a possibility of erroneous judgments. Furthermore, since there are many work steps, it is time consuming and burdensome.

The present invention has been made in view of these conventional problems, and is capable of quickly inspecting and accurately determining whether the contact state of a probe pin with a measurement land of a mounting board to be inspected is good or not. An object of the present invention is to provide an in-circuit tester having a probe pin contact failure determination function.

Means for Solving the Problems Means for achieving the above object will be explained below with reference to FIG. 1 which clearly shows the present invention.

This in-circuit tester, which has a probe pin contact failure judgment function, fixes the board to be tested on a fixture V-, and attaches it to each measurement land to which the leads of each component mounted on the board are connected. In-circuit tester 5 that measures the electrical characteristics of each part by contacting each probe pin and inspects the quality of each part.
6. As a result of these inspections, the probe pin used to measure the component determined to be defective is designated, the designated probe pin is shared to measure the electrical characteristics of other components used for measurement, and the A component inspection means 58 using designated pins inspects the quality, a defective component number counting means 60 counts the number of defective components that share the designated probe pin, and when the number of defective components reaches a predetermined value, the designated probe pins come into contact with each other. The contact failure pin determination means 62 determines that the contact pin is defective.

Function: With the configuration as described above, the quality of each component mounted on the mounting board to be inspected can be inspected using a conventional inspection function. The parts determined to be defective through these inspections include those in which the parts themselves were actually not defective and were measured with the pins in a state of poor contact. Therefore, in order to determine which probe pin has a defective contact state, the specified pin used component inspection means 58 specifies the probe pin used to measure the component determined to be defective, and the specified probe pin is shared for measurement. The electrical characteristics of other components used, that is, all components connected to the same independent pattern, are measured and the quality of these components is inspected. Next, the number of defective parts counting means 60 counts the number of defective parts that share the designated probe pin. Next, the contact failure pin determining means 62 determines that the designated probe pin has a contact failure when the count of defective parts reaches a predetermined value, for example 2. This is because if the count number of a defective component is 1, it cannot be determined whether the component itself is defective or the probe pin has a poor contact, so defective components that are connected to the same independent pattern and share the designated probe pin This is because if it is not 2 or more, it cannot be determined that the designated probe pin has poor contact.

Example Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 2 shows a probe pin contactless state to which the present invention is applied.

FIG. 2 is a block diagram showing an in-circuit tester having a good judgment function. In the figure, 34 is a large number of probe pins provided in the fixture that fixes the mounting board to be tested;
6 is a multiplexer interposed in a channel 38 that connects the probe pin 34 and the measuring section of the main body. These probe pins 34 are brought into contact with corresponding measurement lands of independent patterns on the mounting board. Furthermore, by arbitrarily selecting and switching the multiplexer 36 during measurement, the measuring section and each probe pin 34 can be turned on and off as appropriate.

Further, 40 is a CP that performs necessary processing to measure the electrical characteristics of each component mounted on the mounting board and to inspect the quality of each component itself and the contact state of each probe pin 34.
This is an arithmetic device equipped with tJ.

Furthermore, 42 is a display device such as a CRT that receives output from the device 40 and displays the probe pins 34 that are in poor contact, and 44 is a dot printer that also receives output from the device 40 and records the probe pins 34 that are in poor contact. It is a recording device such as. Note that in order to know which probe pins 34 have poor contact, it is sufficient to have a display device 42 that can easily use a screen, and the recording device 44 is not necessarily required.

The arithmetic device 40 equipped with this CPU includes, for example, a CPU (central processing unit) 46, a ROM (read-only memory) 48,
A microcomputer consisting of a RAM (readable/writable memory) 50, an input/output board 52, a pass line 54, etc. is used.

The CPU 46 corresponds to the central brain of a microcomputer, and according to instructions from a program, controls the entire system, performs arithmetic and logical operations, and temporarily stores the results. It also controls peripheral devices. The ROM 48 stores a control program for controlling the entire in-circuit tester, a component and probe pin contact state determination processing program, and the like.

Further, the RAM 50 stores input data obtained by measuring the electrical characteristics of each component, data of calculation results of the CPU 46, and the like. A probe pin 34, a display device 42, a storage device 44, etc. are connected to the input/output boat 52 via a multiplexer 36. The path line 54 includes an address bus line, a data bus line, a control path line, etc. for connecting these, and is also coupled to peripheral devices.

Next, the operation of this embodiment will be explained.

FIG. 3 is a flowchart i~ consisting of steps P1 to P14 showing an example of a component and probe pin contact state determination processing program. To run this program, first make initial settings necessary for automatically inspecting the quality of each component itself and the contact state of each probe pin. For example, select the measurement mode depending on the component: R for resistance measurement, C for capacitance measurement, 1- for inductance measurement, D for diode characteristic measurement, Z for Zener voltage measurement, S for short circuit inspection measurement, etc. Use mode. Next, go to P2 and set step number △ to 1 in order to automatically inspect the quality of each part. Next, go to P3 and determine whether the step A exceeds the maximum step. If YES, all the inspections of the components mounted on the mounting board have been completed, so the process goes to P4. At P4, execution of the program ends. N.

In this case, go to P5. In P5, it is determined whether the result of inspecting the quality of the parts corresponding to step A is GOOD. YE
In the case of S, the part in step A was determined to be good, so
Go to P6. At P6, 1 is added to step number A, a new step number A is set, and the process returns to P3.

In this way, the quality of each component is sequentially inspected while repeating the steps P3, P5, and P6. Note that if all steps are determined to be GOOD, the mounting board is determined to be a good board, and the inspection ends.

If the test result becomes NG in the process of P5 and the determination is No, the process goes to P7. In this way, a No judgment is made when the measurement mode is 0VER or HIGH (7) in R, UND or LOW (7) in C, and 0V in C.
For ER or HIGH, for D, N00D, for Z, HIGH:Sl:0VER(7), for S, 0PE
This is the case of N. In addition, 0VER indicates when the test result exceeds the test range of the set range, HIGH indicates when the test result is outside the set upper limit, LOW indicates when the test result is outside the set lower limit, and UND indicates When the test result is below the test range of the set range, N00D is 0PE when the test result does not show the saturation characteristics of the diode.
N is a determination that is made when the inspection result is a resistance value higher than a set threshold value, and in both cases, it is impossible to determine whether there is a contact failure or a component failure. In P7, the number of the H-PIN (probe pin on the signal source side) connected to the component in step Δ is specified. Normally, when measuring the electrical characteristics of a component, probe pins are connected to both ends of the component.
(Measurement side) Consider the edge. Next, go to P8.

At P8, the program enters the contact failure probe pin display processing subprogram shown in FIG. First, in p81, it is determined whether the H-PIN with the specified number has already been tested for contact status. If YES, go to P82. At P82, since the contact state of the H-PIN is good, the part is determined to be defective, and the program returns to this program. If No, go to P83. In P83, the step number B is set to 1 and the count number C is set to O. Note that C indicates the number of defective parts that share the designated number day-PIN. Next, go to P84. p84
Then, it is determined whether step B exceeds the maximum step. If no, go to P85. Step B on P85
Determine whether the component is the component whose designated H-PIN number is used for measurement. If No, go to P86.

At p86, 1 is added to step number B, a new value is set, and the process returns to p84. In this way, P84, P
85 and p86 are repeated until YES is determined at p85. If YES in P85, each time step B using the H-PIN with the specified number is reached, go to P87.In P87, the quality of the part using the H-PIN with the specified number is inspected, and if step B is NG. Determine whether Y
For ES, go to p88. In P88, count number G
Add 1 to , set a new C, and go to P86. P8
If No in 7, go to P89. In p89, it is determined that the contact state of the H-PIN is good for the component with step number A, which was previously determined to be No in P5. Next, go to P2O.

P2O determines that the part is defective and returns to this program. This is because if the judgment for other parts that share the H-PIN of the specified number is GOOD, that H-P
This is because IN is not a poor contact.

If the determination is YES in the previous P84, go to P91.

In P91, it is determined whether the count number G is 2 or more. If YES, go to P92. At P92, it is determined that the H-PIN with the designated number has a poor contact, and the program returns to this program.

If NO, go to P89. This is because unless there are two or more defective components that are connected to the same independent pattern and share the designated probe pin, it cannot be determined that the designated probe pin has a contact failure. Since there is no information on other parts connected to the independent pattern, and it is impossible to determine whether the part itself is defective or the probe pin has a poor contact, P2O determines that the part is defective.

Note that later, using a general tester or the like, it is confirmed whether the part is really defective. When you return to this program, go to P9. At P9, press H for the specified number whose contact status was checked first.
- Determine whether the PIN has a poor contact. If YES, go to Plo. In the PIO, the specified H-PIN number is displayed on the screen or recorded on the recording paper as a contact failure. After that, or if No at P9, go to pH together.

Pll specifies the number of the L-PIN (probe pin on the measurement side) connected to the component to the step.

Next, go to PI3. In PI3, the contact failure probe pin display processing subprogram is entered again, but this time the specified number L
- Check the contact status of the PIN in the same way.

After that, return to this program and go to PI3. PI3 determines that the L-PIN of the designated number whose contact status was checked earlier was in poor contact. If YES, PI3
go to In PI3, the specified L-PIN number is displayed as a contact failure on the screen or recorded on the recording paper. after that,
Or, if PI3 is No, both go to P6. In this way, the process is repeated for all steps, and N
Automatically determines whether the G is due to a defect in the component itself or a poor contact with the probe pin.

According to the present invention, which has been described in detail, if a defect is determined as a result of an inspection of the quality of each component mounted on a mounting board to be inspected, it is possible to determine whether the defect is due to a defect in the component itself or whether the probe pin is in contact with the probe pin. Since defects can be automatically determined,
By determining whether the contact state of the probe pin is good or bad in a short time, inspection can be speeded up. In addition, since there is no intervention of human judgment, there are no unstable factors and the test can be performed accurately.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an inserter killer 1 to a tester having a probe pin contact failure determination function according to the present invention. FIG. 2 is a block diagram showing an inser kit tester having a probe pin contact failure determination function to which the present invention is applied. FIG. 3 is a flowchart showing a component and probe pin contact state determination processing program, and FIG. 4 is a flowchart showing a contact failure probe pin display processing subprogram. FIG. 5 is a layout diagram showing a state in which a mounting board to be tested is fixed on a fixture in an in-circuit tester by a press. FIG. 6 is a bottom view showing an example of a single-sided printed circuit board before parts are mounted. 34... Probe pin 40... Device equipped with CPU 42... Display device 44... Recording device 56.
... In-circuit tester 58 ... Means for inspecting components using designated pins 60 ... Means for counting the number of defective parts 62
...Poor contact pin determination means

Claims (1)

[Claims] Fix the board to be tested on the fixture, and touch each probe pin attached to the fixture to each measurement land to which each component mounted on the board connects.
The in-circuit tester measures the electrical characteristics of each component and inspects the quality of each component.Specify the probe pin used to measure the component determined to be defective through those inspections, and then use the specified probe pin. A component inspection means using designated pins that measures the electrical characteristics of other components that are commonly used for measurement and inspects the quality of the component; and a defective component number counting means that counts the number of defective components that share the designated probe pin. 1. An in-circuit tester having a probe pin contact failure determination function, comprising contact failure pin determination means for determining that a designated probe pin has a contact failure when the count number of defective parts reaches a predetermined value.